Today, a graphical description of a business process can be drawn, but it can not be mapped directly to an executable implementation on a workflow engine unless the business process is heavily simplified.
There are two categories of graphical tools for modeling business processes.
Graphical tools of the first category allow a user to describe the process and the behaviors it is intended to show in a completely free manner by using the user's own graphical notation. In this case, the meaning of the symbols in the notation is known only to the user and not by the graphical tool. The user can use the graphical rendering of his notation in the tool to communicate the meaning to other users. But, the user cannot use the graphical rendering to generate workflow code that can be executed on some workflow engine. An example therefor is Microsoft Visio (™ of Microsoft Corp.).
Graphical tools of the second category allow a user to describe the process by using a fixed set of graphical symbols provided by the tool. Before the user can describe the process, he must learn the set of symbols and understand their intended meaning, which is captured in the tool. The graphical tool may also check the user's input whether it complies with modeling rules implemented in the tool. If the user complies with these rules, an executable workflow can be generated with the help of the tool. WBI Modeler in MQ Series Workflow mode (™ of IBM Corporation) is an example therefor.
It is a particular characteristic that tools of the second category allow the user not to describe process flows, using arbitrary graphs. Very often, the flow must be acyclic, i.e. it must not contain loops, when code is to be generated. For example the WBI Modeler allows so called GO TO connectors to implicitly describe cycles, but not in MQ Series Workflow mode. This limitation restricts the freedom of the business process modeler and enforces him to create models which correspond to the abilities of the tool, but not necessarily to the complex reality. From these simplified models, only simplified workflows can be generated, which is a major inhibitor to the adoption of workflow technology today.